NMR studies of three types of highly coordinated organotin hydrides: Chemo-, regio-, and stereoselective reduction of 2,3-epoxy ketones

Article abstract of DOI:10.1021/jo9512416

Three types of highly coordinated organotin hydrides, Bu₂SnIH-Lewis base (Lewis bases; HMPA or tripiperidinophosphine oxide) (type A), Bu₂SnFH-HMPA (type B), and Bu₃SnH-Bu₄NX (X = F, CN) (type C), were characterized as nucleophilic, chelation, and nonchelation types of reductants, respectively, in the reaction with 2,3-epoxy ketones 1. These reagents, which promoted a reduction of the epoxy ring and syn-selective and anti-selective carbonyl reduction, respectively, were spectroscopically confirmed with ¹H, ¹³C, ¹⁹F, and ¹¹⁹Sn NMR and FT-IR. Furthermore, the correlations between their structures and selective reducing abilities were discussed.

Full text of DOI:10.1021/jo9512416

8
2
J . Org. Chem. 1996, 61, 82-87
NMR Stu d ies of Th r ee Typ es of High ly Coor d in a ted Or ga n otin
Hyd r id es: Ch em o-, Regio-, a n d Ster eoselective Red u ction of
2
,3-Ep oxy Keton es
Takayo Kawakami, Ikuya Shibata, and Akio Baba*
Department of Applied Chemistry, Faculty of Engineering, Osaka University,
2
-1 Yamadaoka, Suita, Osaka 565, J apan
Received J uly 11, 1995X
Three types of highly coordinated organotin hydrides, Bu
2
SnIH-Lewis base (Lewis bases; HMPA
SnH-Bu NX (X )
or tripiperidinophosphine oxide) (type A), Bu SnFH-HMPA (type B), and Bu
2
3
4
F, CN) (type C), were characterized as nucleophilic, chelation, and nonchelation types of reductants,
respectively, in the reaction with 2,3-epoxy ketones 1. These reagents, which promoted a reduction
of the epoxy ring and syn-selective and anti-selective carbonyl reduction, respectively, were
1
13
19
119
spectroscopically confirmed with H, C, F, and
Sn NMR and FT-IR. Furthermore, the
correlations between their structures and selective reducing abilities were discussed.
In tr od u ction
Organotin hydrides are advantageous reductants in
terms of their facile availability, moderate stability, and
1
reactivity. Many types of tin hydrides are synthesized
and characterized2 so that they are good candidates for
effective reduction of polar multiple bonds such as
carbonyl groups. However, in most cases, the reductions
-4
3
of organohalides by tri-n-butyltin hydride (Bu SnH) have
been employed under radical conditions,2 and ionic
reductions have not received much attention,2 probably
owing to moderate reactivity of ionic tin hydrides.
,3
,4
F igu r e 1.
Facile and stable complexation with various ligands
is a prevalent feature of organotin compounds, which
to reduce the carbonyl moiety of 2,3-epoxy ketones 1 with
5
8
9c
high anti- and syn-selectivities, respectively (Scheme
).
In this paper, we report a novel tin hydride system,
Bu SnIH-Lewis base (Lewis bases; HMPA or tripiperi-
changes the structure and reactivity of original tin
compounds. On the basis of this concept, we have already
applied the coordinated tin compounds including orga-
1
2
notin hydrides to organic synthesis.6 For example, Bu
-
3
dinophosphine oxide) (type A) (Figure 1a). In contrast
to types B and C, the type A reagents chemo- and
regioselectively reduced the epoxy ring of 2,3-epoxy
ketones 1 without affecting the carbonyl group to give
SnH coordinated by HMPA reduces the carbonyl moiety
of R-halo ketones in contrast to the halide-selective
reduction by noncoordinated Bu
3
SnH.7 In addition, two
types of highly coordinated tin hydrides, the Bu
2
SnFH-
3
-hydroxy ketones 4 (Scheme 1). This reductive selectiv-
8
HMPA (type B) (Figure 1b) and Bu
3
SnH-Bu
4
NX (X )
ity presumably resulted from the activated nucleophilic-
ity of the Sn-I bond. Furthermore, we present the
9
F, CN) systems (type C) (Figure 1c), have been reported
X
Abstract published in Advance ACS Abstracts, November 15, 1995.
(6) We have reported that the reactivity of organotin reagents, such
6
a-d
6e-l
6m-p
(1) (a) Finholt, A. E.; Bond, J r. A. C.; Wilzbach, K. E.; Schlesinger,
as tin halides,
tin enolates, and tin amides
were enhanced by
H. I. J . Am. Chem. Soc. 1947, 69, 2692-2694. (b) Kerk, J . M.; Noltes,
the high coordination. (a) Baba, A.; Shibata, I.; Masuda, K.; Matsuda,
H. Synthesis 1985, 1144-1146. (b) Shibata, I.; Baba, A.; Iwasaki, H.;
Matsuda, H. J . Org. Chem. 1986, 51, 2177-2184. (c) Yano, K.;
Amishiro, N.; Baba, A.; Matsuda, H. Bull. Chem. Soc. J pn. 1991, 64,
2661-2667. (d) Shibata, I.; Yoshimura, N.; Baba, A.; Matsuda, H.
Tetrahedron Lett. 1992, 33, 7149-7152. (e) Baba, A.; Yasuda, M.; Yano,
K.; Matsuda, H. J . Chem. Soc., Perkin Trans. 1 1990, 3205-3207. (f)
Shibata, I.; Nishio, M.; Baba, A.; Matsuda, H. Chem. Lett. 1993, 1219-
1222. (g) Shibata, I.; Nishio, M.; Baba, A.; Matsuda, H. Chem. Lett.
1993, 1953-1956. (h) Shibata, I.; Nishio, M.; Baba, A.; Matsuda, H.
J . Chem. Soc., Chem. Commun. 1993, 1067-1068. (i) Yasuda, M.; Oh-
hata, T.; Shibata, I.; Baba, A.; Matsuda, H. J . Chem. Soc., Perkin Trans.
1 1993, 859-865. (j) Shibata, I.; Baba, A. Org. Prep. Proc. Int. 1994,
26, 85-100. (k) Yasuda, M.; Kato, Y.; Shibata, I.; Baba, A.; Matsuda,
H.; Sonoda, N. J . Org. Chem. 1994, 59, 4386-4392. (l) Yasuda, M.;
Oh-hata, T.; Shibata, I.; Baba, A.; Matsuda, H.; Sonoda, N. Bull. Chem.
Soc. J pn. 1995, 68, 1180-1186. (m) Baba, A.; Kishiki, H.; Shibata, I.;
Matsuda, H. Organometallics 1985, 4, 1329-1333. (n) Shibata, I.;
Toyota, M.; Baba, A.; Matsuda, H. J . Org. Chem. 1990, 55, 2487-2489.
(o) Shibata, I.; Nishio, M.; Baba, A.; Matsuda, H. J . Org. Chem. 1992,
57, 6909-6914. (p) Shibata, I.; Mori, Y.; Baba, A.; Matsuda, H.
Tetrahedron Lett. 1993, 34, 6567-6570.
J . G.; Luijten, J . G. A. J . Appl. Chem. 1957, 366-369.
(2) Pereyre, M.; Quintard, P. J .; Rahm, A. Tin in Organic Synthesis;
Butteworths: London, 1987.
(
3) (a) Neumann, W. P. Angew. Chem. 1963, 225-235. (b) Kuivila,
H. G. Adv. Organomet. Chem. 1964, 1, 47-87. (c) Kuivila, H. G.
Synthesis 1970, 499-509. (d) Fisch, M. H.; Dannenberg, J . J .; Pereyre,
M.; Anderson, W. G.; Rens, J .; Grossman, W. E. L. Tetrahedron 1984,
4
0, 293-297. (e) Neumann, W. P. Synthesis 1987, 665-683. (f) Curran,
D. P. Synthesis 1988, 417-439.
4) High pressure,4a MeOH solvent, silica gel,4c and ZnCl
4b
4d
(
2
catalyst
are also used for ionic reactions, besides transition metal (Pd, Rh)
catalysts.4 (a) Castaing, M. D.; Rahm, A. J . Org. Chem. 1986, 51,
e-h
6
3
65-683. (b) Pereyre, M.; Godet, J . Y. Tetrahedron Lett. 1970, 51,
653-3656. (c) Fung, N. Y. M.; Mayo, P.; Schauble, J . H.; Weedon, A.
C. J . Org. Chem. 1978, 43, 3977-3979. (d) Neumann, W. P.; Heymann,
E. Liebigs Ann. Chem. 1965, 683, 11-23. (e) Zhang, H. X.; Guib e´ , F.;
Balavoine, G. Tetrahedron Lett. 1988, 29, 619-622. (f) Kikukawa, K.
;
(
Umekawa, H.; Wada, F.; Matsuda, T. Chem. Lett. 1988, 881-884.
g) Cochran, J . C.; Bronk, B. S.; Terrence, K. M.; Phillips, H. K.
Tetraheron Lett. 1990, 31, 6621-6624. (h) Zhang, H. X.; Guib e´ , F.;
Balavoine, G. J . Org. Chem. 1990, 55, 1857-1867.
(
5) (a) Zubieta, J . A.; Zuckerman, J . J . Prog. Inorg. Chem. 1978, 24,
(7) Shibata, I.; Suzuki, T.; Baba, A.; Matsuda, H. J . Chem. Soc.,
Chem. Commun. 1988, 882-883.
2
1
51-475. (b) Molloy, K. C. J . Chem. Soc., Dalton Trans. 1988, 1259-
266. (c) Harrison, P. G. Chemistry of Tin; Blackie & Son Limited.:
(8) Kawakami, T.; Shibata, I.; Baba, A.; Matsuda, H. J . Org. Chem.
1993, 58, 7608-7609.
New York, 1989; pp 202-208.
0
022-3263/96/1961-0082$12.00/0 © 1996 American Chemical Society

NMR Studies of Highly Coordinated Organotin Hydrides
J . Org. Chem., Vol. 61, No. 1, 1996 83
Sch em e 1
Ta ble 1. Ch em oselective Ep oxy Red u ction of 2,3-Ep oxy
a
Keton e 1 by Bu 2Sn IH-Lew is Ba se System s
systematic spectral studies of three types of these tin
1
13
19
119
hydrides (types A-C) with H, C, F, and
Sn NMR
and FT-IR and discuss the correlation between their
structures and the divergent selectivities in the reduction
of 1.
a
Epoxy ketone (1), 1 mmol, Bu2SnH2, 0.5 mmol, Bu2SnI2, 0.5
b
c
mmol, Lewis base, 1 mmol, THF, 1 mL. Isolated yield. Tripip-
eridinophosphine oxide. d GLC yield.
Resu lts
Sch em e 2
Ch em oselect ive R ed u ct ion of E p oxid es b y
Bu Sn IH-Lew is Ba se System s (Typ e A). If organotin
2
hydride could possess a Sn-I bond, the reductive cleav-
age of epoxides is expected, because the efficient nucleo-
philic attack of iodide from the Sn-I bond to epoxy rings
has already been demonstrated.6
a,b
2
Fortunately, Bu -
SnIH can be easily prepared by the redistribution reac-
1
0
tion between Bu
found that Bu
reducing ability for aldehydes.11 These facts led us to
expect that Bu SnIH species could reduce the epoxy ring
2
SnH
2
and Bu
2
SnI
2
.
We have recently
2
SnIH characteristically has quite low
2
of 2,3-epoxy ketones 1 in tolerance of the carbonyl group.
The attempt to reduce 1c, however, resulted in a com-
plicated mixture including the carbonyl reduction due to
Ap p lica tion to Ster eocon tr olled Syn th esis of 1,2-
Diols. The stereoselective synthesis of 1,2-diols from 2,3-
epoxy ketone 1e was demonstrated by the combined use
of the three types of tin hydrides (types A-C) (Scheme
2).
a lack of nucleophilicity of the Sn-I bond in Bu
This problem could be resolved by high coordination of
Bu SnIH with HMPA, which chemoselectively reduced
2
SnIH.
2
At the first stage, anti- and syn-2,3-epoxy alcohols 2e
the epoxy ring of 1c without any side reactions (entry 4,
Table 1).
As shown in Table 1, 1a (entry 1), terminal epoxy
ketone 1b (entry 3), and bicyclic epoxy ketones 1c,d
and 3e were prepared in the reduction of 1e with Bu
SnFH-HMPA (type B) via the chelation intermediate
and Bu SnH-Bu NCN (type C) via the nonchelation
intermediate, respectively. Secondly, the isolated prod-
ucts, 2e and 3e, were further reduced by Bu SnIH-
2
-
3
4
(entries 4 and 5) are readily reduced to 3-hydroxy ketones
2
4
a -d . No products arising from the carbonyl reduction
HMPA (type A), providing anti- and syn-1,2-diols, 5 and
6, respectively (86% and 83% yields based on epoxy
alcohols 2e and 3e). In contrast to the reduction of epoxy
ketones 1, the ring-opening took place at the C-3 position
to hydroxy group without any side products. When
were obtained. Noteworthy is the regioselective ring
cleavage at the C2-O bond. In the case of 1a , tripiperi-
dinophosphine oxide is a more effective ligand than
HMPA (entry 2). In contrast to Bu
SnClH-HMPA12 gave a complicated mixture in spite of
the high coordination. The lower chemoselectivity of Bu
2
2
SnIH-HMPA, Bu -
4
LiAlH and DIBAL-H were employed as reducing agents,
-
in contrast to the tin hydrides, mixtures of 1,2-diol and
1,3-diol were obtained from 2,3-epoxy ketones and even
from syn- or anti-2,3-epoxy alcohols.13
2
SnClH-HMPA indicates that the selective ring cleavage
is due to the nucleophilicity of the halide anion.
Sp ect r oscop ic Da t a for Bu
A). We obtained the systematic spectral evidence for Bu
2
Sn IH-H MP A (Typ e
2
-
(9) (a) Shibata, I.; Yoshida, T.; Baba, A.; Matsuda, H. Chem. Lett.
1
991, 307-310. (b) Shibata, I.; Yoshida, T.; Kawakami, T.; Baba, A.;
SnIH and the highly coordinated Bu
shown in Table 2.
2
SnIH-HMPA, as
Matsuda, H. J . Org. Chem. 1992, 57, 4049-4051. (c) Kawakami, T.;
Shibata, I.; Baba, A.; Matsuda, H.; Sonoda, N. Tetrahedron Lett. 1994,
3
5, 8625-8626.
10) (a) Neumann, W. P.; Pedain, J . Tetrahedron Lett. 1964, 2461-
465. (b) Sawyer, A. K.; Brown, J . E.; Hanson, E. L. J . Organomet.
(
4
(13) Epoxy ketone 1a (1 mmol) was reduced at 0 °C by LiAlH (2
2
mmol) in THF (1 mL) to give 1,2-diol (21%, syn:anti ) 26:74) and 1,3-
diol (30% yield, syn:anti ) 13:87). DIBAL-H (1.5 mmol) in toluene
furnished a complex mixture in the reduction of 1a (1.5 mmol). Epoxy
alcohol 2a (0.5 mmol) was reduced at -78 °C by DIBAL-H (0.5 mmol)
in toluene (1 mL) to give 1,2-diol (4% yield) and 1,3-dilol (5% yield).
Chem. 1965, 3, 464-471. (c) Sawyer, A. K.; George, S. M.; Scofield, R.
E. J . Organomet. Chem. 1968, 14, 213-216.
(11) Kawakami, T.; Miyatake, M.; Shibata, I.; Baba, A. J . Org. Chem.
1
996, 61, in press.
12) Kawakami, T.; Sugimoto, T.; Shibata, I.; Baba, A.; Matsuda,
H.; Sonoda, N. J . Org. Chem. 1995, 60, 2677-2682.
(
For the LiAlH
4
reduction of epoxy alcohols, see: Takeshita, M.; Miura,
M.; Unuma, Y. J . Chem. Soc., Perkin Trans. 1 1993, 2901-2905.

8
4
J . Org. Chem., Vol. 61, No. 1, 1996
Kawakami et al.
Ta ble 2. Sp ectr a l Da ta for Bu 2Sn IH, Bu 2Sn IH-HMP A a n d Bu 2Sn F H-HMP A in THF -d 8
Bu2SnIHa
Bu2SnIH-HMPAb
Bu2SnFH-HMPAc
1869.2
7.44
FT-IR (neat)
ν (Sn-H) (cm-1)
1846.1
1857.7
1H NMR
1
δ (Sn- H) (ppm)
6.41
7.18
1
19
Sn NMR
1
19
δ ( Sn) (ppm)
-76.3, d
2060
-169.9, d
2349
-123.0, d
2428
1
1
1
119
1
J ( Sn- H) (Hz)
117
1
J ( Sn- H) (Hz)
1968
2253
2321
13
399 (408/390)d
513e
544(547/541)d
J (Sn- CR) (Hz)
a
.0 M. b 8.2 M. c 8.0 M. d 118Sn/117Sn coupling values resolved. e Average value; 119Sn/117Sn splitting was not resolved.
8
F igu r e 3. 1H-coupled 119Sn NMR spectra: (a) Bu
2
2
SnH , (b)
Bu
2
SnF
2
2 2
+ Bu SnH + HMPA.
cm- also exhibited the inactivation of the Sn-H bond
1
F igu r e 2. 1H-coupled 119Sn NMR spectra: (a) Bu
SnI + Bu SnH , (c) Bu SnI + Bu SnH + HMPA.
2
2 2
SnI , (b) Bu -
by the coordination of HMPA.
2
2
2
2
2
2
2
Sp ectr oscop ic Da ta for Bu
B). The redistribution to Bu SnFH is difficult compared
with that to Bu SnIH because of poor solubility of Bu
We have reported that the formation of Bu
2
Sn F H-HMP A (Typ e
2
A complete transformation from Bu
2
SnH
2
(-205.4
2
2
2
-
-
ppm) and Bu SnI (Figure 2a) to Bu SnIH was confirmed
2
2
2
1
0b
2
SnF .
1
119
with the H-coupled Sn NMR spectra (Figure 2 b). The
addition of an equimolar amount of HMPA to the result-
SnFH swiftly proceeds in the presence of an equimolar
8
amount of HMPA, providing a clear liquid (eq 1).
2
ing Bu SnIH caused not only a considerable upfield shift
of δ(1 Sn) by 93.6 ppm (Figure 2c) but also the increase
19
1
1
1
13
of the values of J (Sn- H) and J (Sn- C) by 289 and
1
14 Hz, respectively (Table 2), indicating the rehybriza-
3
2 14
tion of the tin orbital from sp to sp . The coordination
of the PdO group to the tin atom was also confirmed by
FT-IR spectroscopic data.
Although some spectral studies of Bu
2
SnClH have been
1
5,16
10b,12,19
These data strongly sug-
performed so far,
only one example was reported
1
10b
concerning the H NMR and IR spectra of Bu
Fortunately, we acquired the characteristic spectral data
to confirm the formation of Bu SnFH-HMPA, sum-
marized in Table 2 with the spectral data for Bu SnIH
2
SnFH.
gest the formation of a five-coordinated tin hydride with
a trigonal bipyramidal geometry,1
4,17
where the electrone-
gative ligands, I and HMPA, are presumed to occupy
apical positions as shown in Figure 1a.18 In addition, the
increase of the s-character indicates that the Sn-H bond
2
2
and Bu
Bu SnH
change was observed by mixing the two (see the Experi-
mental Section). No NMR spectral data for Bu SnF
2
SnIH-HMPA. The coordination of HMPA to
2
2
is apparently negligible because no spectral
in Bu
2
2
SnIH-HMPA is less reactive that that in Bu SnIH.
In FT-IR spectroscopy, an increase of ν(Sn-H) by 11.6
2
2
could be obtained even by the addition of HMPA because
of its insolubility.
As shown in Figure 3a, the triplet peak due to Bu -
2
(
14) (a) Holecek, J .; N a´ dvorn ´ı k, M.; Handl ´ı r, K.; Lycka, A. J .
Organomet. Chem. 1983, 241, 177-184. (b) Birchall, T.; Manivannan,
V. J . Chem. Soc., Dalton Trans. 1985, 2671-2675. (c) Edlund, U.;
Arshadi, M.; J ohnels, D. J . Organomet. Chem. 1993, 456, 57-60.
1
119
SnH
NMR spectrum. In contrast, a new doublet peak was
detected when Bu SnH and Bu SnF were mixed in the
presence of HMPA (Figure 3b). At the same time, the
peak due to Bu SnH mostly disappeared. Unfortunately,
the Sn-F coupling could not be detected in either H-
2
appeared at -205.4 ppm in the H-coupled
Sn
(
15) With HMPA, it was difficult to distinguish the PdO absorption;
PO was alternatively employed. When an equimolar amount
PO was added to Bu SnIH (1 mmol) in THF (3 mL), a decrease
hence, Bu
of Bu
of 38.5 cm in the PdO stretching frequency (from 1170.9 cm to
3
3
2
2
2
2
2
-1
-1
1
1
132.4 cm- ) was observed.
16) (a) Kuivila, H. G.; Dixon, J . E.; Maxfield, P. L.; Scarpa, N. M.;
Topka, T. M.; Tsai, K.; Wursthorn, K. R. J . Organomet. Chem. 1975,
2
2
(
1
8
6, 89-107. (b) Chopa, A. B.; Koll, L. C.; Savini, M. C.; Podest a´ , J . C.;
1
119
coupled or H-decoupled Sn NMR spectra because the
widths at half-height are too large, 485 and 417 Hz,
respectively. The presence of the fluorine atom was
Neumann, W. P. Organometallics 1985, 4, 1036-1041. (c) Ayala, A.
D.; Giagante, N.; Podest a´ , J . C.; Neumann, W. P. J . Organomet. Chem.
1
988, 340, 317-329. (d) Podest a´ , J . C.; Ayala, A. D.; Chopa, A. B.;
Giagante, N. N. J . Organomet. Chem. 1989, 364, 39-55.
17) (a) Otera, J . J . Organomet. Chem. 1981, 221, 57-61. (b)
N a´ dvorn ´ı k, M.; Holecek, J .; Handl ´ı r, K.; Lycka, A. J . Organomet. Chem.
19
confirmed by the F NMR spectrum (-163.8 ppm),
(
although the coupling between F and Sn was not ob-
served because of the large width at half-height (1169
1
984, 275, 43-51. (c) Lycka, A.; Holecek, J .; N a´ dvorn ´ı k, M.; Handl ´ı r,
K. J . Organomet. Chem. 1985, 280, 323-329. (d) Holecek, J .; N a´ d-
1
Hz). In the H NMR spectrum, the Sn-H signal due to
vorn ´ı k, M.; Handl ´ı r, K.; Lycka, A. J . Organomet. Chem. 1986, 315,
2
99-308.
(
18) (a) McGardy M. M.; Tobias R. S. J . Am. Chem. Soc. 1965, 87,
(19) (a) Kawakami, K.; Saito, T.; Okawara, R. J . Organomet. Chem.
1967, 8, 377-381. (b) Mitchell, T. N. J . Organomet. Chem. 1973, 59,
189-197.
1
2
909-1916. (b) Barbieri, G.; Taddei, F. J . Chem. Soc., Perkin Trans.
1972, 1327-1331.

NMR Studies of Highly Coordinated Organotin Hydrides
J . Org. Chem., Vol. 61, No. 1, 1996 85
Unfortunately, the direct spectral evidence for the forma-
tion of a stable complex of Bu
obtained. The new peak at ca. -86 ppm in
spectra was proved to be due to a ligand-free Bu
SnSnBu , which was isolated from the reaction mixture
after removal of Bu
NF and HMPA.22 The formation of
Bu SnSnBu supports that the reaction shown in eq 2
3 4
SnH-Bu NF could not be
1
19
Sn NMR
3
-
3
4
3
3
takes place in Bu
3
SnH-Bu NX (X ) F, CN) systems (type
4
C).23
3
When Bu SnH was used alone or with HMPA, no gas
evolution occurred and no peak except for the starting
tin hydride was observed. Therefore, it seems reasonable
that tetrabutylammonium salts greatly activate the
Sn-H bond to such a degree that hydrogen gas evolves
3
from Bu SnH. We presume the reactive species to be
five-coordinate tin hydrides such as Figure 1c.
F igu r e 4. 1H-decoupled 119Sn NMR spectra of an equimolar
mixture of Bu
3 4
SnH and Bu NF in the presence of HMPA.
Discu ssion
Bu SnFH is comprised 90% of the total Sn-H signal.
These results indicate the effective formation of Bu
SnFH.
2
NMR studies indicate that Bu SnIH-Lewis base com-
2
2
-
plex (type A) has a trigonal bipyramidal geometry il-
lustrated in Figure 1a. In this geometry, the nucleophi-
licity of iodide in the complex would be enhanced most
effectively by Lewis base coordinating in a straight line.
Furthermore, FT-IR spectra indicate that the nucleophi-
The next problem to be resolved is whether or not
HMPA coordinates to Bu SnFH because no spectral data
of a ligand-free Bu SnFH can be obtained. The large
2
2
1
1
1
13
coupling constant values, J (Sn- H) and J (Sn- C),
strongly suggest the formation of a complex in compari-
licity of hydride in Bu SnIH-Lewis base is decreased by
2
the coordination of Lewis base. Both activation of the
Sn-I bond and deactivation of the Sn-H bond by Lewis
base probably contribute to the selective nucleophilic
attack of iodide to epoxy rings prior to the carbonyl
reduction by hydride.
son with those of Bu
isolate a ligand-free Bu
2
SnIH-HMPA. An attempt to
SnFH was unsuccessful because
2
removing HMPA from Bu
washing with H O led to white solids, corresponding to
Bu SnF , and Bu SnH as confirmed by FT-IR. This fact
indicates that the redistribution shown in eq 1 is revers-
ible and that the unstable Bu SnFH produced is stabi-
2
SnFH-HMPA system by
2
2
2
2
2
3 2 2
Neither Bu SnH nor Bu SnH could reduce the epoxy
ring of 1c at room temperature even in the presence of
HMPA. This result indicates that the cleavage of epoxy
rings by the Sn-I bond is an essential step to achieve
epoxide reductions. The reaction path would be explain-
able as follows. At first, an iodohydrin intermediate is
produced by nucleophilic attack of iodide from the Sn-I
bond to the epoxy ring (eq 3).24 Then, the resulting alkyl
2
lized by the coordination of HMPA. Next, we confirmed
the coordination from the PdO group to the tin atom of
Bu
instead of HMPA. When an equimolar amount of Bu
PO (1 mmol) was added to the mixture of Bu SnH (0.5
mmol) and Bu SnF (0.5 mmol) in THF (3 mL), the
decrease of 42.4 cm in the PdO stretching frequency
1170.9 to 1128.5 cm-1) was observed. Such a decrease
strongly suggests the coordination of the PdO group to
Bu SnFH-
SnFH.16 The above results indicate that Bu
HMPA is a five-coordinate tin hydride (Figure 1b).
NMR Stu dies of th e Bu Sn H-Bu NF System (Type
C). Both Bu SnH-Bu NCN and Bu SnH-Bu NF afford
the syn-selective carbonyl reduction of 2,3-epoxy ketones
2 3
SnFH with FT-IR spectroscopy by employing Bu PO
3
-
2
2
2
2
-
1
(
2
2
3
4
3
4
3
4
2
0
1
.
We tried to obtain spectral evidence for the actual
reducing species generated by the mixing of Bu SnH and
Bu NF. The mixing of both compounds at ambient
3
4
temperature caused the evolution of gas, which was
further accelerated by the addition of HMPA. So, we
stirred an equimolar mixture of Bu
3
SnH and Bu
4
NF at
iodide group is reduced by the intramolecular (or inter-
-
78 °C in the presence of HMPA and monitored the mode
1
19
-
of the reaction with
Sn NMR shown in Figure 4.
(21) The peak due to Bu SnF at -20 °C in the Bu SnH-Bu NF
3
2
3
4
(
1:1) system (1.03 M with respect to tin hydride species in THF-d ):
8
The peak of Bu SnH (-90.3 ppm) gradually decreased
3
1
9 1 19 119 1 19 117
F NMR δ -137.4 ppm (s, J ( F- Sn) ) 1815 Hz, J ( F- Sn) )
as the temperature was raised and completely disap-
peared at ambient temperature. A new peak (in the
range from -84 to -88 ppm) increased gradually. Fur-
thermore, a small peak (-157.8 ppm, triplet at -30 °C)
119
19
119
1
734 Hz); Sn NMR δ -155.6 ppm (t). For the F and
Sn NMR
-
spectra of Ph SnF
3 2
see: Gingras, M.; Chan, T. H.; Harpp, D. N. J .
Org. Chem. 1990, 55, 2078-2090.
(
(
22) See the Experimental Section.
23) In addition to Bu SnH-Bu NF, the evolution of gas was
SnH (3.1 mmol) was added at room temperature
3
4
-
21
was detected which would be assigned as Bu
3
SnF
2
.
observed when Bu
to a solution of Bu
spectrum was recorded at rt:
) 2589 Hz, Bu SnSnBu ).
(24) No iodohydrin intermediate could be isolated.
3
1
19
4
NCN (2.8 mmol) in THF-d
8
(1 mL).
Sn NMR
1
19
1
119 119
Sn NMR δ -84.3 (s, J ( Sn- Sn)
(
4
20) For example, in the reduction of 2,3-epoxy ketone 1a , Bu
NF provided syn-2,3-epoxy alcohol 3a in 76% yield (82% de).
3
SnH-
3
3
Bu

8
6
J . Org. Chem., Vol. 61, No. 1, 1996
Kawakami et al.
molecular) tin hydride moiety, providing an alcohol after
quenching with MeOH.
nucleophilicity of the iodide atom in the apical position
is activated most greatly by the coordination of HMPA
to cleave the epoxy ring effectively. Type B reagent, Bu
2
-
In the reaction of 2,3-epoxy ketones 1, the ring cleavage
takes place at the C2-O bond adjacent to the CdO group
to provide 3-hydroxy ketones 4, while the nucleophilic
attack to the C-3 position occurs in the reaction of 2,3-
epoxy alcohols 2e and 3e. This change of regioselectivity
can be explained only presumably in this stage. The
SnFH-HMPA, bears strong Lewis acidity and forms a
chelate intermediate with 1 to provide anti-2,3-epoxy
alcohols 2. The Lewis acidity of the tin atom of type B
can be increased by the electronegative fluorine substitu-
ent in spite of the coordinated disturbance by HMPA.
Type C reagents, Bu
3
SnH-Bu NX (X ) F, CN), act as
4
cleavage of the latter epoxides seems to proceed via a
general nucleophilic attack.25 On the other hand, the
typical hydride donors and reduce 2,3-epoxy ketones 1
to give syn-2,3-epoxy alcohols 3 in excellent yields
because of a “non-chelation” reduction of the carbonyl
moieties by the activated Sn-H bond.
cleavage of the C2-O bond of the former is due to the
coordination of only the carbonyl oxygen to the tin atom
because of the low acidity of Bu SnIH-HMPA. Predomi-
2
nant cleavage at the C3-O bond has been reported when
both carbonyl and epoxy oxygens can coordinate to metal
halides.26
Exp er im en ta l Section
An a lysis. 1H, 13C, 19F, and 119Sn NMR spectra were
recorded at 400, 100, 376, and 149 MHz, respectively. Samples
The complex, Bu
scopically confirmed to be a five-coordinate tin hydride,
and its structure can be inferred from that of Bu SnIH-
HMPA (type A), as shown in Figure 1b. Although the
Sn-F bond in Bu SnFH-HMPA may be somewhat
2
SnFH-HMPA (type B), is spectro-
1
13
for H and C, NMR spectra of produced alcohols were
examined in deuteriochloroform (CDCl ) containing 0.03% (w/
2
3
1
13
119
v) of tetramethylsilane. Samples for H, C, and Sn NMR
spectra of tin hydrides were examined in tetrahydrofuran-d
containing tetramethyltin. Samples for 19F NMR spectra of
tin hydrides were measured relative to external fluorobenzene
2
8
activated by the coordination of HMPA as in type A, only
the carbonyl groups of 1 to anti-2,3-epoxy alcohols 2 were
reduced without cleavage of epoxy rings because of the
inherent low nucleophilicity of fluoride.8 The stereo-
chemical outcome is explainable by assuming Cram’s
chelation model (Scheme 1).27 In fact, when the reduction
8
in tetrahydrofuran-d . GLC analyses were performed with a
FFAP (2-m × 3-mm glass column). Column chromatography
was performed by using Wakogel C-200 mesh silica gel.
Preparative TLC was carried out on Wakogel B-5F silica gel.
Yields were determined by 1H NMR or GLC using internal
of 1e was carried out by Bu
3
SnH in the presence of ZnCl
2
standards.
as a representative chelating reagent, the anti-selective
carbonyl reduction proceeded via Cram’s chelation model
Ma ter ia ls. Tri-n-butyltin hydride (Bu SnH) and di-n-
3
butyltin dihydride (Bu
the reduction of tri-n-butyltin chloride (Bu
2
SnH
2
) were, respectively, prepared by
SnCl) and di-n-
(
46% yield, anti:syn ) 88:12). That the high Lewis
3
2 2 4
SnCl ) with LiAlH
.3 Di-n-butyltin
0
butyltin dichloride (Bu
halide hydrides (Bu SnXH; X ) Cl, I) were synthesized by the
redistribution reaction between Bu
SnXH-HMPA (X ) F, I) was synthesized by the redistribution
reaction between Bu SnH and Bu SnX in the presence of
acidity of the tin center in Bu SnFH-HMPA increased
2
2
by the highly electronegative fluorine substituent is quite
possibly the reason why this chelation model is taken on
in spite of the coordinate disturbance by HMPA.28
1
0a
2
SnH
2
and Bu
2
SnX
2
.
2
Bu -
2
2
2
2
A five-coordinated structure for Bu
3
SnH-Bu
4
NX (X )
HMPA. 2,3-Epoxy ketones 1 were prepared by the oxidation
of the corresponding 2,3-unsaturated ketones using alkaline
hydrogen peroxide.31 THF was freshly distilled over sodium
benzophenone ketyl, and HMPA was distilled over finely
powdered calcium hydride. All reactions were carried out
under dry nitrogen.
F, CN) (type C) is plausibly assumed as illustrated in
Figure 1c. The Sn-H bond in the complex would be
activated by ligands more effectively than the bonds in
type A and type B since it lies in an apical position only
in type C. Therefore, the type C reagent acts as a typical
hydride donor to reduce the carbonyl groups of 2,3-epoxy
ketones 1 to syn-2,3-epoxy alcohols 3 via the non-
chelation model (Felkin-Anh model)29 (Scheme 1). In
general, a high degree of syn-selective carbonyl reduction
of epoxy ketones 1 has not been achieved due to the
difficulty of the complete removing of the coordination
from epoxy oxygen to metal hydrides. The successful syn-
selective reduction by the type C system strongly sug-
gests the formation of an anion type of tin hydride
Rep r esen ta tive P r oced u r e for Ch em oselective Red u c-
tion of Ep oxid e. To the solution of Bu SnH (0.5 mmol) in 1
2 2
mL of THF were added Bu SnI2 (0.5 mmol) and HMPA (1
2
9c
mmol). The mixture was stirred at room temperature for 10
min. 2,3-Epoxy ketone 1 (1 mmol) was added at 0 °C, and
then the solution was stirred until the Sn-H absorption (1858
-
1
cm ) disappeared in the IR spectrum. After quenching with
MeOH (5 mL), volatiles were removed under reduced pressure.
The residue was subjected to column chromatography, eluting
with hexane-EtOAc (1:2), to give a crude product 4. Further
purification of 4 was performed by TLC, eluting with hexane-
diethyl ether (1:1).
-
+
3 4
complex like as [Bu SnXH] [Bu N] (X ) F, CN).
Con clu sion . Systematic spectral studies of three
different types (type A-C) of organotin hydrides have
clarified the origins of their divergent reducing charac-
3-Hyd r oxy-1-p h en yl-1-bu ta n on e (4a ): colorless liquid; IR
-
1 1
(
)
1
7
1
1
neat) 3300 and 1650 cm ; H NMR (CDCl
6.35 Hz), 3.05 (dd, 1H, J ) 8.79 and 17.58 Hz), 3.17 (dd,
H, J ) 2.93 and 17.58 Hz), 3.35 (br, 1H), 4.37-4.45 (m, 1H),
3
) δ 1.30 (d, 3H, J
teristics. Type A reagent, Bu
nucleophilic iodide donor and reduces the epoxy ring of
chemo- and regioselectively. This complex is proved
to have a trigonal bipyramidal geometry in which the
2
SnIH-HMPA, acts as a
13
.44-7.96 (m, 5H); C NMR (CDCl ) δ 22.39, 46.47, 63.97,
28.01, 128.64, 133.48, 136.67, 200.77; HRMS calcd for C10
64.0838, found 164.0831.
3
12 2
H O
1
3-Hyd r oxy-1-p h en yl-1-p r op a n on e (4b): colorless liquid;
-
1 1
IR (neat) 3300 and 1670 cm ; H NMR (CDCl
3
) δ 3.22 (t, 2H,
J ) 5.37 Hz), 4.02 (t, 2H, J ) 5.37 Hz), 7.43-7.97 (m, 5H);
C NMR (CDCl ) δ 40.36, 57.98, 127.97, 128.61, 133.44,
136.60, 200.38; HRMS calcd for C
150.0681.
(
25) (a) Smith, W. B. J . Org. Chem. 1984, 49, 3219-3220. (b) Ranu,
B. C.; Das, A. R. J . Chem. Soc., Chem. Commun. 1990, 1334-1335.
26) Otsubo, K.; Inanaga, J .; Yamaguchi, M. Tetrahedron Lett. 1987,
8, 4435-4436.
27) Cram, D. J .; Elhafez, F. A. A. J . Am. Chem. Soc. 1952, 74,
828-5835.
28) It is not clear for the formation of Cram’s chelation model
1
3
3
(
9 10 2
H O 150.0681, found
2
(
5
(
(30) (a) Finholt, A. E.; Bond, J r. A. C.; Wilzbach, K. E.; Schlesinger,
H. I. J . Am. Chem. Soc. 1947, 69, 2692-2696. (b) Kerk, G. J . M.; Noltes,
J . G.; Luijiten, J . G. A. J . Appl. Chem. 1957, 7, 366-369.
(31) Hasegawa, E.; Ishiyama, K.; Horaguchi, T.; Shimizu, T. J . Org.
Chem. 1991, 56, 1631-1635.
whether the transition state is a seven-coordinate complex or the ligand
exchange between HMPA and epoxy oxygen of 1 occurs.
(29) Cherest, M.; Felkin, H.; Prudent, N. Tetrahedron Lett. 1968,
1
8, 2199-2203.

NMR Studies of Highly Coordinated Organotin Hydrides
-Hyd r oxy-1-cycloh exa n on e (4c): colorless liquid; IR
J . Org. Chem., Vol. 61, No. 1, 1996 87
3
Bu
2
Sn H
2
. In a small flask, Bu
in 0.5 mL of THF-d
2
SnH
2
(3.96 mmol) was kept
Sn; 0.8 mL
-
1 1
(
neat) 3305 and 1690 cm ; H NMR (CDCl
3
) δ 1.66-2.34 (m,
H), 2.42 (dd, 1H, J ) 7.32 and 14.16 Hz), 2.66 (dd, 1H, J )
.91 and 14.16 Hz), 4.17-4.22 (m, 1H); 13C NMR (CDCl
) δ
0.64, 32.79, 40.92, 50.42, 69.75, 209.95; HRMS calcd for
114.0681, found 114.0682.
-Hyd r oxy-1-cyclop en ta n on e (4d ): colorless liquid; IR
under dry N
2
8
containing Me
4
7
3
2
of the solution was transferred to a 5 φ NMR tube. NMR
1
3
spectra were recorded at room temperature (24 °C): H NMR-
1
119
1
(7.91 mmol in 1 mL of THF-d ) δ 4.47 (Sn-H, J ( Sn- H) )
13 1 119
8
1
117
1
C
6
H
10
O
2
1681 Hz, J ( Sn- H) ) 1606 Hz); C NMR (rt) δ 7.6 ( J (
-
1
3
) ) 376 Hz, 1J ( Sn- C
117
13
3
Sn- C ) ) 359 Hz), 14.3, 27.7
R
R
-
1
1
3 13 2 13 119
(
neat) 3350 and 1680 cm ; H NMR (CDCl
3
) δ 2.02-2.50 (m,
( J (Sn- C
γ
) ) 58 Hz), 31.3 ( J (Sn- C
â
) ) 24 Hz); Sn NMR
H), 3.15 (br, 1H), 4.59-4.63 (m, 1H); 13C NMR (CDCl
) δ
(rt) δ -205.4 (t); FT-IR (neat) ν(Sn-H) ) 1836.5 cm .
-1
6
3
1
3
1
19
1.83, 35.48, 47.58, 69.34, 218.59; HRMS calcd for C
00.0524, found 100.0502.
5
H
8
O
2
Bu Sn I2 (8.00 mmol in 1 mL of THF-d ); Sn NMR (rt) δ
2
8
-57.7 (s).
Bu
Ster eoselective Syn th esis of 1,2-Diols. To the solution
of Bu SnF (1 mmol) in 1 mL of THF was added Bu SnH (1
1
2
Sn IH (8.00 mmol in 1 mL of THF-d
8
); H NMR (rt) δ
2
2
2
2
6
.41 (Sn-H, J ( Sn- H) ) 2060 Hz, J ( Sn- H) ) 1968 Hz);
1
119
1
1
117
1
mmol) and HMPA (2 mmol). The mixture was stirred at room
temperature for 10 min. 1,3-Diphenyl-2,3-epoxy-1-propanone
13
13
1
119
13
1
117
R
C NMR (rt) δ 14.1, 17.3 ( J ( Sn- C ) ) 408 Hz, J ( Sn-
2 13
3
13
C
R
) ) 390 Hz), 26.7 ( J (Sn- C
γ
) ) 74 Hz), 29.7 ( J (Sn- C
â
)
1
e (2 mmol) was added, and the mixture was stirred until the
119
)
1
29 Hz); Sn NMR (rt) δ -76.3 (d); FT-IR (neat) ν(Sn-H) )
-1
Sn-H absorption (1869 cm ) disappeared in the IR spectrum.
After the reaction was quenched with MeOH (5 mL), volatiles
were removed under reduced pressure. The residue was
subjected to column chromatography, eluting with hexane-
EtOAc (1:1), to give an anti-rich mixture of alcohols 2e and
846.1 cm-1.
Bu Sn IH-HMP A (8.17 mmol in 1 mL of THF-d
1
2
8
117
); H NMR
1
119
1
1
1
(
2
2
rt) δ 7.18 (Sn-H, J ( Sn- H) ) 2349 Hz, J ( Sn- H) )
13
1
13
253 Hz); C NMR (rt) δ 14.4, 23.7 ( J (Sn- C
R
) ) 513 Hz),
3
13
119
7.1 ( J (Sn- C
γ
) ) 84 Hz), 29.5; Sn NMR (rt) δ -169.9 (d);
3
e (91:9). Further purification of diastereomers was performed
by TLC, eluting with hexane-diethyl ether (1:1).
A solution of Bu NCN (2 mmol) in THF (2 mL) was stirred
at -78 °C. Bu SnH (2 mmol) and 1,3-diphenyl-2,3-epoxy-1-
propanone 1e (2 mmol) were added. Stirring was continued
-1
FT-IR (neat) ν(Sn-H) ) 1857.7 cm
Bu Sn H
.
1
2
2
-HMP A (8.34 mmol in 1 mL of THF-d
8
117
); H NMR
4
1
119
1
1
1
(
1
rt) δ 4.46 (Sn-H, J ( Sn- H) ) 1670 Hz, J ( Sn- H) )
3
1
3
1
119
13
1
117
596 Hz); C NMR (rt) δ 7.7 ( J ( Sn- C
R
) ) 378 Hz, J (
-
1
3
3
13
Sn- C
R
13
) ) 361 Hz), 14.3, 27.7 ( J (Sn- C
γ
) ) 57 Hz), 31.3
-
1
until the Sn-H absorption (1809 cm ) disappeared in the IR
spectrum. After the reaction was quenched with MeOH (5
mL), volatiles were removed under reduced pressure. The
residue was subjected to column chromatography, eluting with
hexane-EtOAc (1:1), to give a syn-rich mixture of alcohols,
2
119
(
J (Sn- C
neat) ν(Sn-H) ) 1836.5 cm
Bu Sn F H-HMP A (7.96 mmol in 1 mL of THF-d
â
) ) 24 Hz);
Sn NMR (rt) δ -204.5 (t); FT-IR
-
1
(
.
1
2
8
117
); H NMR
1
119
1
1
1
(
rt) δ 7.44 (Sn-H, J ( Sn- H) ) 2428 Hz, J ( Sn- H) )
1
3
1
119
2
321 Hz, w1/2 ) 4.4 Hz); C NMR (rt) δ 14.4, 19.8 ( J ( Sn-
1 117 13 3 13
2
e and 3e (14:86).
1
3
C
R
) ) 547 Hz, J ( Sn- C
R
) ) 541 Hz), 27.7 ( J (Sn- C
γ
) )
) ) 29 Hz); Sn NMR (rt) δ -123.0
(d, w1/2 ) 485 Hz); 19F NMR (3.99 mmol in 1 mL of THF-d
rt) δ -163.8 (br, w1/2 ) 1169 Hz); FT-IR (neat) ν(Sn-H) )
a n ti- a n d syn -1,3-Dip h en yl-2,3-ep oxy-1-p r op a n ol (2e
2
13
119
-
1
82 Hz), 28.9 ( J (Sn- C
â
a n d 3e): pale yellow liquid; IR (neat) 3400 cm ; HRMS calcd
1
8
,
for C15
14 2 3
H O 226.0994, found 226.0999; H NMR (CDCl ) 2e:
δ 2.57 (d, 1H, J ) 2.44 Hz), 3.28 (dd, 1H, J ) 1.95 and 2.93
Hz), 4.13 (d, 1H, J ) 1.95 Hz), 4.98 (dd, 1H, J ) 2.44 and 2.93
Hz), 7.23-7.44 (m, 10H); 3e: δ 2.77 (br, 1H), 3.29 (dd, 1H, J
-
1
1
869.2 cm
.
1
Bu Sn H (5.98 mmol in 1 mL of THF-d
3
8
); H NMR (rt) δ
1
119
1
1
117
1
4
.772 (1H, J ( Sn- H) ) 1594 Hz J ( Sn- H) ) 1524 Hz,
)
)
1.95 and 4.88 Hz), 4.00 (d, 1H, J ) 1.95 Hz), 4.70 (d, 1H, J
1
19
1
119
1
13
Sn-H); Sn NMR δ -90.3 (d, J ( Sn- H) ) 1595 Hz).
Bu Sn H-Bu NF . To a solution of Bu NF (1.00 mmol) in
THF-d (1 mL) was added Bu SnH (1.07 mmol) at -78 °C in
the presence of HMPA (2.01 mmol). NMR spectra were
4.88 Hz), 7.22-7.46 (m, 10H); C NMR (CDCl ) 2e δ 55.0,
3
6
3
1
4.9, 71.2, 125.7, 126.5, 128.3, 128.3, 128.5, 128.7, 136.5, 139.2;
e δ 56.9, 65.7, 73.3, 125.7, 126.2, 128.2, 128.4, 128.5, 128.7,
36.3, 140.1.
3
4
4
8
3
1
19
The solution of the isolated product 2e or 3e (1 mmol) in
recorded at variable temperatures:
Sn NMR (-30 °C) δ
1
119
1
1 119
THF (1 mL) was added to the mixture of Bu
2
SnH
2
(0.5 mmol)
-88.5 (s), -89.6 (d, J ( Sn- H) ) 1565 Hz), -157.3 (t, J (
-
1
9
119
and Bu SnI (0.5 mmol) in the presence of HMPA (1 mmol).
2
2
Sn- F) ) 1826 Hz); Sn NMR (-15 °C) δ -87.3 (s), -89.5
1 119 1 1 119 19
Stirring was continued at 70 °C for 3 h. After the reaction
was quenched with MeOH (5 mL), volatiles were removed
under reduced pressure. The residue was subjected to column
chromatography, eluting with hexane-EtOAc (1:1), to give a
anti-rich or a syn-rich mixture of 1,2-diols, 5 (91:9) or 6 (13:
(d, J ( Sn- H) ) 1568 Hz), -156.8 (t, J ( Sn- F) ) 1816
19 1 119 1
Hz); 1 Sn NMR (-5 °C) δ -86.4 (s), -89.4 (d, J ( Sn- H) )
1
119
19
119
1624 Hz), -155.4 (t, J ( Sn- F) ) 1815 Hz); Sn NMR (rt)
1
119
19
δ -84.1 (s), -152.7 (t, J ( Sn- F) ) 1799 Hz).
Bu Sn Sn Bu . The NMR spectrum of a THF-d
ca. 1 mmol of Bu SnSnBu isolated from the mixture of Bu
SnH-Bu NF and HMPA was recorded at rt:
3
3
8
solution of
8
7). Further purification of diastereomers was performed by
3
3
3
-
1
19
TLC, eluting with hexane-diethyl ether (1:1). The stereo-
4
1
Sn NMR δ
1
119
119
chemistry of diastereomers was assigned by H NMR in
-84.4 (s, J ( Sn- Sn) ) 2574 Hz); HRMS calcd for C24
Sn 582.2272, found 582.2263. Commercially available Bu
SnSnBu
H
53
-
-
comparison with stereochemically defined authentic samples.13
2
3
1
19
a n ti-1,2-Dih yd r oxy-1,3-d ip h en ylp r op a n e (5): colorless
3
(8.07 mmol in 1 mL of THF-d
-84.2 (s, J ( Sn- Sn) ) 2589 Hz).
8
); Sn NMR (rt) δ
-
1
1
1
119
119
liquid, purified by TLC; IR (neat) 3300 cm ; H NMR (CDCl
δ 1.94 (d, 1H, J ) 3.91 Hz), 2.56 (d, 1H, J ) 3.42 Hz), 2.63
dd, 1H, J ) 9.77 and 13.68 Hz), 2.72 (dd, 1H, J ) 3.91 and
3.68 Hz), 4.01-4.07 (m, 1H), 4.77 (dd, 1H, J ) 3.42 and 3.90
3
)
(
1
Ack n ow led gm en t. This work was financially sup-
ported by the J SPS Fellowships for J apanese J unior
Scientists and a Grant-in Aid for Scientific Research on
Priority Area of Reactive Organometallics No. 05236102
from the Ministry of Education, Science and Culture.
Thanks are due to Mrs. Y. Miyaji and Mr. H. Moriguchi,
Faculty of Engineering, Osaka University, for assistance
in obtaining NMR and HRMS spectra.
1
3
Hz); C NMR (CDCl
27.90, 128.44, 128.54, 129.36, 138.30, 140.26; HRMS calcd
for C15 228.1151, found 228.1131.
syn -1,2-Dih yd r oxy-1,3-d ip h en ylp r op a n e (6): colorless
3
) δ 37.60, 76.02, 76.32, 126.47, 126.70,
1
16 2
H O
-1
3
liquid, purified by TLC; IR (neat) 3300 cm ; 1H NMR (CDCl )
δ 2.51 (d, 1H, J ) 3.91 Hz), 2.59 (dd, 1H, J ) 8.79 and 13.67
Hz), 2.67 (dd, 1H, J ) 3.91 and 13.67 Hz), 3.05 (d, 1H, J )
3
.90 Hz), 3.85-3.91 (m, 1H), 4.46 (dd, 1H, J ) 3.91 and 6.34
13
Hz); C NMR (CDCl
1
3
) δ 39.32, 76.70, 76.84, 126.41, 126.85,
Su p p or tin g In for m a tion Ava ila ble: Copies of 1H and 13C
28.04, 128.44, 128.50, 129.29, 1138.09, 140.90; HRMS calcd
NMR spectra of 2e, 3e, 4a -d , 5, and 6 (14 pages). This
material is contained in libraries on microfiche, immediately
follows this article in the microfilm version of the journal, and
can be ordered from the ACS; see any current masthead page
for ordering information.
for C15
16 2
H O 228.1151, found 228.1160.
1
H, 13C, F , a n d
19
119
Sn NMR Stu d ies. Chemical shifts for
Sn. Chemi-
1
119
H and Sn NMR were measured relative to Me
4
1
3
8
cal shifts for C NMR were measured relative to THF-d .
Chemical shifts for F NMR were measured relative to
external fluorobenzene.
1
9
J O9512416